A camera may be used to measure a gap between different blades of a machine such as a gas turbine. When the machine is in operation, gaps between adjacent blades may change their widths during different phases of operation, for instance as a result of changed temperature, changed pressure or operational stresses. Detecting and accurately measuring these gaps can provide relevant information about operating conditions and machine performance. Measuring a gap accurately and automatically is challenging even with known main axis of orientation of the parts. For instance, an infra-red camera is used to measure a gap in a hot environment of a turbine. Accurately detecting and measuring the gap with an infra-red camera is challenging because the infra-red images have low contrast, and the signal to noise ratio (SNR) is low. Furthermore, it is preferred to monitor such a gap over a significant period of time of uninterrupted operation. Simple and effective methods and apparatus to automatically measure gaps in an uninterrupted in hot operating environments are believed currently not to exist.
Accordingly, novel and improved apparatus and methods are required to accurately and automatically measure and monitor in a non-contact manner a gap between parts in a machine in a hot operating environment are required.